New high-speed communication services called “Long Term Evolution” (LTE) have been introduced in recent years as a new standard for mobile communication systems such as cellular phone networks. LTE-Advanced system, an enhanced version of LTE, has also been discussed in the 3rd Generation Partnership Project (3GPP).
Further, the International Telecommunication Union Radio Communications Sector (ITU-R) has decided to discuss the LTE-Advanced system as a proposal for IMT-Advanced system which enhances the International Mobile Telecommunication 2000 (IMT-2000).
Typical IMT-2000 systems include wideband code-division multiple access (W-CDMA), cdmaOne, and Worldwide Interoperability for Microwave Access (WiMAX) systems.
The development of LTE-Advanced is based on the LTE system and includes the study of introducing Multimedia Broadcast Multicast Service Single Frequency Network (MBSFN). With this MBSFN, a plurality of base stations transmit the same Multimedia Broadcast Multicast Service (MBMS) data, and the multicast data is wirelessly forwarded by intermediate devices (relay stations). Also investigated are extension of uplink and downlink bandwidths and introduction of multiple-input multiple-output (MIMO) uplink.